I need help in using Impulse Force (2D)

I am a beginner at Unity, so I am just trying to do some basic stuff. I wanted to try to make a bar move horizontally in 2D mode, and I did it. Then I noticed it was taking time to start moving,accelerate, and change direction because it follows force = mass x acceleration, but I don't want that. With the docs and scripting API, I found that I should use a 2D Impulse force to solve my problem. I just don't know how to fix my current code to use the impulse force instead, even though I have tried it many times in different ways. This is the code I am using:

    using UnityEngine;
         using System.Collections;
         
         public class Control : MonoBehaviour {
             
             
             public float speed;
             
             private Rigidbody2D rb;
             
             void Start ()
             {
                 rb = GetComponent<Rigidbody2D>();
             }
             
             void FixedUpdate ()
             {
                 float moveHorizontal = Input.GetAxis ("Horizontal");
         
                 
                 Vector2 movement = new Vector2 (moveHorizontal, 0);
                 
                 rb.AddForce (movement * speed);
             }
         }